Solution
Step 1
Obey the multiplication law of indices where
[tex]a^b\times a^{d\text{ }}=a^{b+d}[/tex]So that we will have
[tex]5\times3\times10^{13}\times10^{15}[/tex][tex]\begin{gathered} 15\times10^{13+15} \\ =15\times10^{28} \end{gathered}[/tex]